Sunday, November 4, 2012

A very strong cold front and upper-level weather system will move across the central Plains and Midwest this coming Saturday, and the Mississippi, Tennessee, Ohio Valley region back into the southern Plains this coming Sunday. These systems will bring a threat of severe weather ahead of them, and much colder conditions behind them.

Below is the U.S. GFS computer model forecast valid at 6pm CST on Saturday. The cold front is shown in blue, the warm front in red. The area outlined in red has the highest chance of strong to severe thunderstorms on Saturday afternoon and evening:

This threat will progress East on Saturday night and Sunday, encompassing the area outlined in red on the image below, valid 6pm CST on Sunday:

We will need to closely monitor this situation as the lower through middle-level wind fields will be more than sufficient for severe storms including tornadoes within the areas indicated above. The main question will be how far North the most unstable low-level airmass will be able to establish itself, which will be supportive of the most intense storms. Fortunately we have several more days to monitor this situation, and we'll be sure to keep you updated.

Behind this system, much colder air will invade the region. The GFS computer model forecast departure from normal temperatures valid Monday, November 12th, shows below normal values across much of the western three-quarters fo the Continental U.S.:

We will continue to monitor this situation and bring you additional, more specific updates over the coming days.

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